There have been proposed an image reading apparatus capable of driving a feeding device (feeding unit), which feeds a sheet-shaped document to a reading unit such as CIS, and a moving device (carriage), which moves the reading unit, with power from one motor. According to the image reading apparatus, a position of a planet gear that transmits a driving force of the motor, is switched between a feeding unit-side position, at which the planet gear transmits the power to the feeding unit, and a carriage-side position, at which the planet gear transmits the power to the carriage. Thereby, it is possible to operate the feeding unit and the carriage by one motor.